1. Field of the Invention
The present invention relates to an image pickup apparatus with wide angle zoom lens system having a reflecting surface in an optical path.
2. Description of the Related Art
In recent years, digital cameras in which, an object is photographed by using an image pickup element such as a CCD (Charge Coupled Device) and a CMOS (Complementary Metal-Oxide Semiconductor) have been main stream replacing a silver-salt film camera, and such digital cameras have been used in wide range of categories from a high-function type for professional use to a portable popular type.
Particularly, among the digital cameras of the popular type, small size products, particularly a slim digital camera which can be accommodated easily in a pocket of clothes or a bag, and carried conveniently have been preferred. Moreover, as a taking lens system, a magnification ratio of about 3 for a zoom lens system has been common. It is necessary to make small a size of a zoom lens system compatible with such camera, such that a portability of the camera is not lost.
Moreover, for slimming the camera, it is necessary to slim a lens barrel of the zoom lens system. As a means thereof, a so-called collapsible barrel which is pushed out from an inside of a camera body when the camera is in use, and is accommodated inside the camera body while carrying the camera has been common. On the other hand, an inner zoom type which makes reflect an optical path through roughly 90° by using a reflecting optical member in a lens unit nearest to an object in a zoom lens system, and carries out zooming by using a lens unit closer to an image side than that lens unit has been proposed.
A peculiarity of the inner zoom type is that, a full length of the lens system does not change at the time of zooming. Therefore, since it is possible to make a thickness of a lens barrel in a direction of a thickness of a camera to be about a thickness of a lens nearest to the object side, the slimming of the camera can be carried out easily. Moreover, for making the size small, a zoom lens system of a four unit structure having an arrangement of lenses having a positive, negative, positive, and positive refracting power in order from the object side has been proposed in Japanese Patent Application Laid-open Publication Nos. 2003-302576, 2004-69808, 2004-184627, 2004-347712, and 2006-343622.
Moreover, zoom lens systems of a conventional technology in which, a lens structure has positive, negative, positive, and positive refracting power in order from the object side, a magnification ratio of about 3, and a half-image angle of 35° and more has been disclosed in Japanese Patent Application Laid-open Publication Nos. 2000-131610 and 2006-58363.